He was evaluated for a rib-cage strain Sunday morning and Farrell said Mujica won’t need to be placed on the disabled list.

“Give him today and tomorrow to continue to receive treatment and see where we are when we open up against Cincinnati [Tuesday night],” Farrell said.

In 10 innings, Mujica has given up 10 earned runs, 16 hits, four walks, and a home run.

In spring training, Farrell said he would use Mujica as the primary closer when
Koji Uehara wasn’t available. In April, Uehara was shut down for three days with shoulder soreness.

Should either be unavailable at any point, Farrell said he would choose a closer based on matchups.

“Without saying that this is the Closer B, we would go more matchup,” Farrell said.

Roles in the bullpen are still fluid, Farrell continued.

“Depending on where we are in the lineup, it’s going to determine who that seventh or eighth inning [guy] is going to be,” he said. “We’ve seen [Junichi] Tazawa in the seventh or eighth inning if we’re against righthanders. [Andrew] Miller or even [Chris] Capuano in the eighth if we’re working against lefties. So we’ll match up more in those innings prior to Koji.”

Farrell said he wants to get Craig Breslow into that mix as well. Breslow has made six appearances since coming off the disabled list April 9. He bounced back from a four-run outing against the Yankees April 24 with a clean inning Friday against the A’s.

“He went through a stretch where he didn’t get much work,” Farrell said. “We know for us to perform to our abilities we’ve got to get him in the mix. Two days ago with his outing, he’s getting closer to what we became accustomed to last year.

“When he was activated, he was still in that arm-strength building phase, and I can’t say that he’s all the way there yet, but two days ago was a step in the right direction.”

Pierzynski connects

With Mike Napoli out of the starting lineup, Farrell went with A.J. Pierzynski in the cleanup spot, and Pierzynski came through in the seventh inning with his first home run in 168 career at-bats at Fenway Park.

“It’s nice to finally get one,” Pierzynski said. “I’ve played a lot of games here.”

Pierzynski’s reached base safely in eight of his past 10 games, hitting .371 with two doubles, two homers, and nine RBIs.

“He’s been swinging the bat well,” Farrell said. “He’s in the middle of our offense. When we’re able to put some runs up on the board, A.J. seemingly is in there somewhere.”

Napoli came in to play first in the ninth inning after Jonathan Herrera ran for Mike Carp. With an offday Monday, Farrell’s plan was to give Napoli the day to get treatment for the left ring finger he dislocated in April.

“He’s still trying to get over some of the things he’s been banged up with,” Farrell said. “If you noticed, after every at-bat he’s getting taped up with that finger. So it’s something that he still contends with. It speaks to his pain threshold, which is obviously high.”

Farrell marvels

A day after Jon Lester’s career-high 15-strikeout gem, in which he gave up one hit in eight innings, Farrell was still marveling.

“That’s a rare performance,” the manager said. “The thing that still stands out is that combination of power and command.”

In his last three innings, Lester threw 32 of his 49 pitches for strikes. In the eighth inning, he was still topping out at 92 miles per hour.

“When you see the location and the quality location of some of the pitches inside the strike zone, that’s what’s remarkable,” Farrell said.

“To maintain that kind of power through a full eight innings and nearly 120 pitches, he got into a really good rhythm and carried it all the way through.”

What was more astonishing to Farrell, though, was looking back and realizing a career night for Lester was a common occurrence for former Red Sox great Pedro Martinez.

“What puts some other things in context, Pedro did that 10 times,” Farrell said. “He’s much more consistent to the arm side of the strike zone. It makes you take a step back and realize how dominant a pitcher he was as well.”

Into it

When Nate Moulter, one of the operators of the scoreboard along the Green Monster, came out in a Bruins jersey and updated the score of Saturday’s 5-3 win over the Canadiens, the eruption from the crowd struck Farrell.

“[Pitching coach] Juan [Nieves] and I were talking about it in the dugout as it was happening,” Farrell said. “Even before the man behind the Wall in the Bruins jersey came out, the crowd reaction told us what was taking place.”

There were more than a few Bruins jerseys scattered through Fenway Park during the Sox’ 6-3 win on Saturday.

“We were just kind of marveling at the fans here are into everything and if people in the ballpark here that are paying close attention to what’s going on down at the Garden, it’s just an example of how passionate they are and how in tune they are with all sports and all teams in this city,” Farrell said.